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References: <20230309183812.299349-1-zyytlz.wz@163.com>
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From:   Zheng Hacker <hackerzheng666@gmail.com>
Date:   Fri, 10 Mar 2023 02:46:09 +0800
Message-ID: <CAJedcCy-b5aCi33FV84WtOSQXOf3YrEGheOAKdBSzBHdv4bG4w@mail.gmail.com>
Subject: Re: [PATCH] scsi: qla4xxx: Fix use after free bug in
 da9150_charger_remove due to race condition
To:     Zheng Wang <zyytlz.wz@163.com>
Cc:     njavali@marvell.com, mrangankar@marvell.com,
        GR-QLogic-Storage-Upstream@marvell.com, jejb@linux.ibm.com,
        martin.petersen@oracle.com, linux-scsi@vger.kernel.org,
        linux-kernel@vger.kernel.org, 1395428693sheep@gmail.com,
        alex000young@gmail.com
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Sorry about the fix. This is a false positive which should be ignored.
The work will be posted on ha->dpc_thread. In qla4xxx_remove_adapter,
it will call destroy_workqueue(ha->dpc_thread);

Regards,
Zheng

Zheng Wang <zyytlz.wz@163.com> =E4=BA=8E2023=E5=B9=B43=E6=9C=8810=E6=97=A5=
=E5=91=A8=E4=BA=94 02:38=E5=86=99=E9=81=93=EF=BC=9A
>
> In qla4xxx_probe_adapter, &ha->dpc_work is bound with
> qla4xxx_do_dpc. qla4xxx_post_aen_work may be called
> to start the work.
>
> If we remove the module which will call qla4xxx_remove_adapter
>   to make cleanup, there may be a unfinished work. The possible
>   sequence is as follows:
>
> Fix it by canceling the work before cleanup in qla4xxx_remove_adapter
>
> CPU0                  CPUc1
>
>                     |qla4xxx_do_dpc
> qla4xxx_remove_adapter|
> scsi_remove_host        |
> kfree(ha->host)         |
>                     |
>                     |   iscsi_host_for_each_session
>                     |   //use ha->host
> Fixes: afaf5a2d341d ("[SCSI] Initial Commit of qla4xxx")
> Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
> ---
>  drivers/scsi/qla4xxx/ql4_os.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/scsi/qla4xxx/ql4_os.c b/drivers/scsi/qla4xxx/ql4_os.=
c
> index 005502125b27..d530cc853f43 100644
> --- a/drivers/scsi/qla4xxx/ql4_os.c
> +++ b/drivers/scsi/qla4xxx/ql4_os.c
> @@ -9001,6 +9001,7 @@ static void qla4xxx_remove_adapter(struct pci_dev *=
pdev)
>         if (!pci_is_enabled(pdev))
>                 return;
>
> +       cancel_work_sync(&ha->dpc_work);
>         ha =3D pci_get_drvdata(pdev);
>
>         if (is_qla40XX(ha))
> --
> 2.25.1
>